1. Field of the Invention
The present invention relates to a parabolic-reflector antenna for receiving satellite broadcasts, and more particularly to a primary horn for use in such a parabolic-reflector antenna.
2. Description of the Prior Art
Parabolic-reflector antennas are used to receive satellite broadcasts. As shown in FIG. 1 of the accompanying drawings, one conventional parabolic-reflector antenna comprises a parabolic reflector 1 for reflecting an incoming radio wave, and a polarization converter 2 for converting the radio wave reflected by the parabolic reflector 1 from circular polarization into linear polarization. The parabolic reflector 1 is of a circular shape (i.e., a circular aperture) as viewed from the broadcasting satellite. The polarization converter 2 comprises a primary horn which also has a circular aperture for guiding the radio wave reflected by the parabolic reflector 1 to a polarization converting system.
Since the conventional parabolic-reflector antenna has the parabolic reflector 1 of a circular aperture, if the parabolic-reflector antenna faces a plurality of broadcasting satellites that are located relatively close to each other, it tends to receive radio waves from those broadcasting satellites which the antenna is not aimed at.